The present invention relates to vacuum cleaners. More particularly, the present invention relates to upright vacuum cleaners used for suctioning dirt and debris from carpets and floors.
Upright vacuum cleaners are well known in the art. The two major types of these vacuum cleaners are a soft bag vacuum cleaner and a hard shell vacuum cleaner. In the hard shell vacuum cleaner, a vacuum source generates the suction required to pull dirt from the carpet or floor being vacuumed through a suction opening and into a filter bag housed within the hard shell upper portion of the vacuum cleaner.
To avoid the need for vacuum filter bags, and the associated expense and inconvenience of replacing the bag, another type of upright vacuum cleaner utilizes cyclonic air flow, rather than a filter bag, to separate the majority of the dirt and other particulates from the suction air stream. The air is then filtered to remove residual particulates, returned to the motor and exhausted.
For many of the prior art cyclonic air flow vacuum cleaners, the process of emptying the dirt collection container has been found inconvenient and often resulted in the spillage of the cup contents. Also, the replacement of filter elements in these units has not been convenient.
In some cyclonic air flow vacuum cleaners, the exhaust air is not free of residual contaminants. Because the cyclonic action of such conventional cyclonic vacuum cleaners does not completely remove all dust, dirt and other contaminants from the suction air stream, it is necessary to include a filter downstream from the cyclonic chamber. However, the conventional filter elements so used have caused considerable difficulty. A conventional filter which is sufficiently fine to filter the air stream effectively, unduly restricts air flow and decreases the effectiveness of the cyclonic action. On the other hand, a coarse filter does not effectively filter the air stream of residual contaminants. Furthermore, conventional filter media, such as paper or fibrous media, has been found to clog readily thereby unduly decreasing air flow rates over time.
One known vacuum cleaner design disclosed by the Model MC-110U product sold by National of Japan. This design is to an upright vacuum cleaner having a nozzle base with a handle pivotally attached to the nozzle base. Secured to the handle is an upper housing including a motor and a filter chamber. The filter chamber includes a dust cup and filter element mounted to the dust cup via a filter cage. The filter element appears to have a pleated filter medium. The dust cup appears to have an inlet opening at its base and an outlet opening at its open upper end The filter cage and filter element are mounted to the open end of the dust cup. The motor of the National '110U product appears to be located above the dust cup.
Accordingly, it has been deemed desirable to develop a new and improved upright vacuum cleaner having a cyclonic air flow which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.